Area Forecast Discussion
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000 FXUS61 KPBZ 252207 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 607 PM EDT MON MAY 25 2015 .SYNOPSIS... WARMTH AND HUMIDITY HAVE RETURNED TO THE UPPER OHIO VALLEY REGION...BUT SHOWER AND THUNDERSTORM CHANCES CAN BE EXPECTED FOR MOST OF THE COMING WEEK. && .NEAR TERM /THROUGH TUESDAY/...
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THE UPDATE FOR THE EVENING FEATURES FAIRLY SMALL ADJUSTMENTS TO POPS AS A WEAK VORT RIBBON MOVING ACROSS EASTERN OHIO WITH STRONG SOUTHWESTERLY FLOW AND WARM ADVECTION HAS YIELDED NO THUNDERSTORM ACTIVITY DUE TO WARM TEMPERATURES ALOFT. LIKEWISE...CONVECTIVE SHOWERS SEEM TO HAVE SLIPPED MOSTLY NORTH OF THE AREA AT THE MOMENT...AS SUCH POPS HAVE BEEN CUT BACK FOR THE EVENING HOURS AS THIS FEATURE DOES SEEM TO WEAKEN SUBSTANTIALLY THROUGH THE REMAINDER OF THE EVENING. THE FORECAST THINKING OF ANOTHER INCREASE IN POPS TOWARD MORNING STILL SEEMS ON TARGET PER THE 18Z NAM GUIDANCE AS ANOTHER SHORT WAVE RIDES NORTHEASTWARD. POPS WERE MAINTAINED FOR THIS. HOWEVER...IN THE INTERIM BETWEEN NOW AND THEN...SKIES WERE REDUCED FOR MOST AREAS TO BE GENERALLY PARTLY CLOUDY THROUGH THE BULK OF THE EVENING AND EARLY OVERNIGHT PERIOD. FRIES
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&& .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/... CONTINUED SOUTHWEST FLOW WILL MAINTAIN THE FUNNEL OF DEEP MOISTURE OVER THE UPPER OHIO REGION...AT LEAST UNTIL THE ADVANCING MID LEVEL TROUGH AXIS PROGRESSION SHUNTS THE PLUME EASTWARD BY THURSDAY AS PER THE GFS AND NAM SOLUTIONS. CHANCE...TO LIKELY SHOWER AND THUNDERSTORM WILL THUS BE MAINTAINED FOR THE PERIOD. THE BEST OVERALL POPS AT MOMENT ARE STILL PROGGED FOR WEDNESDAY...ALTHOUGH TODAYS MODEL RUNS ARE FASTER IN PUSHING THE PARENT MID/UPR LEVEL TROUGH AXIS AND SUSTAINED MOISTURE TAP EASTWARD...SO THOSE LIKELY NUMBERS WERE TRENDED SLIGHTLY EASTWARD AS WELL. THE SHORT TERM SEVERE POTENTIAL STILL LOOKS TO BE COMPROMISED BY WARM MID LEVELS AND A MARGINAL DEEP LAYER SHEAR PROFILE...BUT WARM RAIN PROCESSES AND TRAINING MAY SUPPORT LOCALLY HEAVY RAINFALL UNTIL MOISTURE AND WARM CLOUD DEPTH WANES LATER ON WEDNESDAY. NO MAJOR CHANGES WERE NEEDED FOR THE SEASONABLY WARM TEMP PROGNOSIS. && .LONG TERM /FRIDAY THROUGH MONDAY/... PRECIP CHANCES WILL INCREASE AGAIN FOR THE WEEKEND...AND PERSIST INTO NEXT WEEK AS MODELS AGREE ON A WEAK SPLIT FLOW REGIME CONVERGING OVER THE GREAT LAKES/UPPER OHIO REGION. THE SURFACE FRONT IS PROJECTED TO SAG SOUTHWARD UNTIL REDEVELOPING NORTHWARD AS A WARM FRONT IN RESPONSE TO GREAT PLAINS TROUGHING EARLY NEXT WEEK. GIVEN MODEL MAGNITUDE...POSITIONING...AND TIMING DISPUTES...PERSISTENCE WILL RULE THE LONG TERM FORECAST STRATEGY. && .AVIATION /22Z MONDAY THROUGH SATURDAY/... GENLY VFR IS EXPECTED TO CONTINUE THROUGH TONIGHT AS THE ERODING UPPER RIDGE OVER THE REGION SUPPRESSES CONVECTION. HOWEVER...ISOLATED...TO SCATTERED SHOWERS WILL INCREASE LOCAL RESTRICTION POTENTIAL AND MOIST SOUTHERLY FLOW MAY SPAWN A STRATUS/STRATOCU LAYER EARLY ON TUESDAY. TAFS THUS INCLUDE A VICINITY SHOWER MENTION AND A LATE PERIOD...LOW END VFR CLOUD BASE FORECAST AS A LOW CONFIDENCE HEDGE. .OUTLOOK.../MONDAY THROUGH FRIDAY/... ABUNDANT MOISTURE AND DISTURBANCES IN SOUTHWEST FLOW ARE LIKELY TO SPAWN PERIODIC RESTRICTIONS THROUGH WEDNESDAY. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$

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